Correction of ADC Errors by Additive Iterative Method with Dithering

The iterative method could be used for automatic accuracy improvement of a measurement system. In its application for analog-to-digital converter (ADC) a quantization error represents a limitation for the correction process. Therefore, combination of correction methods is common for ADC error correction. Combination of the additive iterative method (AIM) with nonsubtractive dithering (ND) has been proposed for slow measurement based on ADC where errors could change in time. The principle of combination of both techniques is described in the paper. AIM is based on precise inverse element (IE). In the designed system the IE output signal is created by pulse width modulation and low-pass filtering. A technique similar to deterministic dithering is employed to achieve precise processing of signal from IE. Analysis of influence of stochastic dither upon the results of correction is performed with the aim to find optimal parameters of ND. Finally, dependency of the root mean squared error and error dispersion on the measured value is drawn to show how AIM corrects the nonlinear deterministic error but slightly increases system noise.